Quartz Crystal Microbalance with Dissipation Monitoring (EQCM-D) for in-situ studies of electrodes for supercapacitors and batteries: A mini-review

•In-situ real-time monitoring of rough/porous structure.•Authentic electrodes in contact with electrolyte solutions by EQCM-D.•Mesoscopic hydrodynamic probing of even minute effects.•Tracking of intercalation-induced dimensional changes in energy-storage electrodes.•Quantification of electrode deformations via quartz crystal admittance analysis.

Herein the application of a recently introduced new method of tracking in-situ the intercalation-induced deformations of supercapacitor and Li-battery electrodes is reviewed. The method is based on the use of multi-harmonic electrochemical quartz microbalance with dissipation monitoring, EQCM-D (in-situ hydrodynamic spectroscopy) which enables a permanent control of the electrodes' state-of-health by probing their mechanical properties. The potential-dependent frequency and resonance width changes are fitted to a chosen hydrodynamic admittance model allowing thus quantification of the electrode deformations under different charging conditions. Intercalation of different alkaline metal cations into layered MXene electrode serves as a readily understandable working example of quantifying such electrodes deformations. Further method developments including in-situ viscoelastic characterization of composite porous electrodes are envisaged in the near future.

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